1. Field of the Invention
The present disclosure relates generally to exercise machines. More particularly, the invention is directed to an improved weight resistance apparatus for assisting a trainer to generate a maximum positive force from a user.
2. Description of the Related Art
Enhancing performance via strength and conditioning training of muscles is the goal of many professional athletes and trainers as well as weekend warriors. It is known that there are three distinct phases in the movement of muscles and tendons, an eccentric contraction (extending the muscle), an isometric contraction (no movement), and a concentric contraction (contracting the muscle).
An eccentric contraction is the motion of an active muscle while it is lengthening under load. During an eccentric contraction, the muscles lengthen while producing force, usually by returning from a shortened (concentric) position to a resting position. Eccentric training focuses on slowing down the elongation of the muscle process in order to challenge the muscles, which can lead to stronger muscles, faster muscle repair and increasing metabolic rate. Eccentric training is particularly good for casual and high performance athletes or the elderly and patients looking to rehabilitate certain muscles and tendons.
An isometric contraction is a type of strength training in which the joint angle and muscle length do not change during contraction. Thus, isometrics occur in static positions, rather than being dynamic through a range of motion.
A concentric contraction occurs when the muscle shortens. Concentric contractions are the most common types of muscle activation athletes perform in a gym when lifting weights. Concentric contraction is also known as muscle shortening. Concentric contractions are common to many sports in which a subject needs to generate a lot of power or explosive force. Common exercises that cause concentric contractions include the lifting phase of a bicep curl, a squat or a pull up. Running up a hill or climbing stairs also causes the quadriceps to contract concentrically.
It is known that a subject's body can tolerate up to 1.75 times more weight eccentrically than it can concentrically. Thus, for example whereas a subject can exert approximately 500 pounds of force eccentrically, the same subject could only exert approximately 300 pounds concentrically. Therefore, when bench pressing a fixed weight of 300 pounds in a single load bearing movement using free weights as in a bench press, a subject will not be maximizing his or her eccentric load bearing force.
Maximizing eccentric load bearing training is the goal of adaptive stimulus and is ideal for maximizing strength, power and hypertrophy gains. The more intense eccentric training, that is, resisting weight as it comes down, the quicker and greater the results of achieving strength and conditioning training of muscles.
Free weights are excellent for increasing strength, however a distinct disadvantage of free weights is that they provide the same amount of resistance for the entire repetition and no resistance between repetitions. For example, after you perform the uplift on a bicep curl, there is no resistance during the pause.
Resistance training is effective in increasing eccentric force. It is known in the art to use bands and elastics to effect resistance training. For example, as you stretch an elastic band, it provides more resistance.
However, a disadvantage of elastics and exercise bands is that they do not provide as much resistance as heavy free weights and weight machines. Thus, resistance bands may not be a good choice for achieving strength-training goals.
Thus, it is desirable to have a device that will train the body using an effective resistance apparatus that also achieves strength training goals that allow the muscles to exert maximum concentric (pushing weight away from body), eccentric (resisting as it comes down) and isometric force throughout an entire load bearing exercise or repetition.